When using the .Crop function with the same width (or height) as the source width (or height) , the returned result is one pixel smaller.
Dim img As New WriteableBitmap(100, 100)
Dim img2 As WriteableBitmap = img.Crop(0, 0, 50, 50)
'Correct : returns a 50x50 image
Dim img3 = img.Crop(0, 0, 100, 50)
'Bug? : returns a 99x50 image , expected 100x50
Dim img As New WriteableBitmap(100, 100)
Dim img2 As WriteableBitmap = img.Crop(0, 0, 50, 50)
'Correct : returns a 50x50 image
Dim img3 = img.Crop(0, 0, 100, 50)
'Bug? : returns a 99x50 image , expected 100x50